Also known as: Prostate cancer
Sheldon is diagnosed with intermediate-grade prostate cancer (Gleason score 6) that has not metastasized. He struggles throughout the episode with treatment decisions (surgery with risk of incontinence/impotence, active surveillance, or radiation therapy) and the impact on his relationship with Laura.
Also known as: Breast cancer
Miranda is a violin teacher undergoing chemotherapy for breast cancer that has metastasized to her brain, making her terminal. She is receiving radiation therapy to delay progression long enough to attend her niece's college graduation. Her evolving friendship with Sheldon during daily radiation sessions is a central emotional thread of the episode.
Also known as: Pedophilia
Nick is Sheldon's patient with pedophilic urges who was previously suicidal. Throughout the episode, Sheldon becomes convinced Nick has kidnapped missing child Sarah Nelson and is holding her captive. The episode climaxes with Sheldon having Nick involuntarily committed and discovering Sarah locked in Nick's basement.
Also known as: Suicide attempt
Nick has a history of suicidal ideation and a previous suicide attempt (overdose) that brought him to Sheldon's care. Sheldon uses concerns about acute suicidality to justify a 5150 psychiatric hold that allows police to search Nick's home and find Sarah.